When I was working in a dermatology academic lab, and then in cosmetic industry, I remember that we obtained nomal dermal fibroblasts by letting them migrate out from a fresh skin explant in a petri dish with accurate medium. Did you know that procedure ? Best regards. Philippe Chadebech
I digest for 1 hour, but I heavily slice and macerate the skin sample before digestion. I assume you're using 1 mg/ml collagenase? I've always had a lot of cell death leaving the digestion longer than 1 hr.
I'd recommend mechanically disrupting your skin sample, digesting for 1hr, and then running flow cytometry and seeing how many live dermal fibs you recover.